Frequency alignment and switch-over in power supplies

ABSTRACT

An apparatus includes a power converter and a controller. The power converter converts a received input voltage into an output voltage that powers a dynamic load. The controller controls a setting of a switching frequency applied to the power converter. During one operational mode, the controller transitions a setting of the switching frequency of the power converter from a first clock frequency signal to a second clock frequency signal depending on occurrence of phase alignment of the second clock frequency signal and the first clock frequency signal, which may eventually occur over multiple switching control cycles. Transition of the switching frequency from the first clock frequency signal to the second clock frequency signal at or around a time of the phase alignment reduces possible perturbations in the output voltage as a result of the clock frequency switchover.

BACKGROUND

In many conventional applications, voltage regulators (VRs) need tosynchronize their control signals such as pulse width modulation pulsesto a master external synchronizing clock. This occurs in thetelecommunication market where electro-magnetic noise is a concern andbeat frequencies arising out of closely spaced switching frequencies arenot tolerated.

In certain instances, a voltage regulator needs to deviate from thefrequency dictated by the master external clock. For example, a voltageregulator switches to use of a frequency other than the master clockduring a Transient Response (TR) or if it operates in DiscontinuousConduction Mode (DCM). When the TR condition or DCM is over, the voltageregulator needs to operate off the external sync clock again.

BRIEF DESCRIPTION

This disclosure includes the observation that conventional power supplycontrol techniques suffer from deficiencies. For example, abrupt powersupply switching frequency transitions negatively impact an ability toproduce a steady output voltage.

Additionally, it should be noted that it is not simple to shift PWMcontrol pulses to align such signals with respect to a master clock.This is because in many voltage regulator architectures, the timing andsequence of pulses are very important. If the controller is operated toabruptly switchover from a temporary clock to using the master clockwithout consideration of phase differences, there is a danger that thecontroller might generate a wrong duty cycle, saturate a respectivetransformer of the power supply, saturate a respective output inductor,violate dead times, etc.

Embodiments herein include novel ways of controlling multiple phases andphase resynchronization in a power supply to produce an output voltage.For example, a controller as described herein provides a novel way oftransitioning control of a power converter from a first switch frequencyto a second switch frequency based on detected phase alignment asfurther discussed herein.

More specifically, embodiments herein include an apparatus. Theapparatus includes a power converter and a controller. During operation,the power converter is operative to convert a received input voltageinto an output voltage that powers a dynamic load. The controllercontrols a setting of a switching frequency applied to control switchingoperation of the power converter. For example, during one operationalmode, the controller transitions the setting of the switching frequencyof the power converter from a first clock frequency (signal) to a secondclock frequency (signal) depending on phase alignment of the first clockfrequency (signal) and the second clock frequency (signal).

In one embodiment, during an asynchronous operational mode, the firstclock frequency signal and the second clock frequency signal are notaligned. However, because the first clock frequency signal and thesecond clock frequency signal are different settings (one larger thanthe other), eventually the first clock frequency signal and the secondclock frequency signal align over multiple switching control cycles. Thetransition of the switching frequency from the first frequency signal tothe second frequency signal (master frequency signal) at or around thetime of alignment substantially reduces or prevents perturbations in theoutput voltage (and/or disturbance to the circuit) as a result of theclock frequency transition.

In accordance with further embodiments, the second clock frequencysignal as described herein is a predetermined fixed (master) frequencyused to control switching operation of the power converter duringnon-transient load conditions. In response to detecting a condition suchas a change in an amount of current consumed by a load, variation in amagnitude of the output voltage, or any other power supply condition,the controller temporarily sets the switching frequency of the powerconverter to the first clock frequency signal (asynchronous mode, whichis possibly needed) to maintain regulation of the output voltage withina desired range due to a transient condition.

In one non-limiting example embodiment, the controller switches overfrom setting the switching frequency from the second clock frequencysignal (master clock frequency) to the first clock frequency signal(asynchronous clock frequency) in response to detecting a change incurrent consumption by the dynamic load.

In one embodiment, the first clock frequency signal is greater in value(such as greater in magnitude) than the second clock frequency signal toprovide better transient response. For example, operation of the powerconverter at the higher switching frequency increases a responsivenessof the power converter to maintain the output voltage in regulationduring transient current consumption conditions.

If desired, the controller varies a value (a.k.a., setting) of the firstclock frequency signal as well as corresponding pulse width modulationsignals applied to the power converter to maintain a magnitude of theoutput voltage within a desired operational range.

In accordance with still further embodiments, after the detected triggercondition or conditions are eliminated or reduced while operating thepower converter at the first clock frequency, the controller initiatesswitchover back to the second clock frequency (master clock frequency).In one embodiment, to assist in a smooth switchover from operating offthe first clock frequency signal to operating off the second clockfrequency signal, the controller monitors the phase alignment of thefirst clock frequency and the second clock frequency as previouslydiscussed. In one embodiment, the phase alignment (between the firstclock frequency and second clock frequency) changes over each of themultiple control cycles until, eventually, the phase of the second clockfrequency substantially aligns with the first clock frequency. Asfurther discussed herein, at or around such time of detecting alignment,the controller initiates switchover from the first clock frequency tothe second clock frequency.

Accordingly, in one embodiment, the controller transitions the settingof the switching frequency from the first clock frequency to the secondclock frequency depending on a phase difference between the first clockfrequency with respect to the second clock frequency, the phasedifference decreasing in magnitude over multiple switching controlcycles until switchover as previously discussed.

In yet further example embodiments, a value (setting) of the first clockfrequency is set to a value that is different, but substantially equalto a value (setting) of the second clock frequency. That is, the firstclock frequency and the second clock frequency are not equal inmagnitude. In one embodiment, the difference in the values of the firstclock frequency and the second clock frequency (one frequency beinggreater than the other) eventually causes the phases of the differentclock frequency signals to align, enabling transition as describedherein.

In accordance with still further embodiments, the controller sets thefirst clock frequency signal and the second clock frequency signal todifferent desired fixed frequency settings just prior to the transitionof setting the switching frequency to the second clock frequency signal.More specifically, in one non-limiting example embodiment, thecontroller adjusts a value (setting) of the first clock frequency to be(an intermediate frequency) within a threshold value (such as 20%percent of point of the first clock frequency or other suitable value)of the second clock frequency in response to detecting a trigger eventto set the switching frequency of the power converter back to the secondclock frequency.

In yet further example embodiments, as previously discussed, thecontroller transitions from setting the switching frequency from thefirst clock frequency to the second clock frequency in response to thecontroller (or other suitable resource) detecting that a phase of thesecond clock frequency aligns with a phase of the first clock frequencyor that a phase of the first clock frequency aligns with a phase of thesecond clock frequency.

In still further example embodiments, the second clock frequency is amaster clock frequency; the first clock frequency is asynchronous withrespect to the master clock frequency.

As previously discussed, embodiments herein are useful over conventionaltechniques. For example, control of the switching frequency associatedwith the power converter enables quicker synchronization of operatingthe power converter off a master clock frequency within a predeterminednumber of switching control cycles. As further discussed herein, theasynchronous clock frequency signal can be adjusted (such as increasedor decreased) to facilitate a faster or slower transition switchoverfrom the temporary clock frequency to the master clock frequency.

These and other more specific embodiments are disclosed in more detailbelow.

Note that although embodiments as discussed herein are applicable topower converters, the concepts disclosed herein may be advantageouslyapplied to any other suitable topologies as well as general power supplycontrol applications.

Note that any of the resources as discussed herein can include one ormore computerized devices, mobile communication devices, servers, basestations, wireless communication equipment, communication managementsystems, workstations, user equipment, handheld or laptop computers, orthe like to carry out and/or support any or all of the method operationsdisclosed herein. In other words, one or more computerized devices orprocessors can be programmed and/or configured to operate as explainedherein to carry out the different embodiments as described herein.

Yet other embodiments herein include software programs to perform thesteps and operations summarized above and disclosed in detail below. Onesuch embodiment comprises a computer program product including anon-transitory computer-readable storage medium (i.e., any computerreadable hardware storage medium) on which software instructions areencoded for subsequent execution. The instructions, when executed in acomputerized device (hardware) having a processor, program and/or causethe processor (hardware) to perform the operations disclosed herein.Such arrangements are typically provided as software, code,instructions, and/or other data (e.g., data structures) arranged orencoded on a non-transitory computer readable storage medium such as anoptical medium (e.g., CD-ROM), floppy disk, hard disk, memory stick,memory device, etc., or other a medium such as firmware in one or moreROM, RAM, PROM, etc., or as an Application Specific Integrated Circuit(ASIC), etc. The software or firmware or other such configurations canbe installed onto a computerized device to cause the computerized deviceto perform the techniques explained herein.

Accordingly, embodiments herein are directed to methods, systems,computer program products, etc., that support operations as discussedherein.

One embodiment herein includes a computer readable storage medium and/orsystem having instructions stored thereon. The instructions, whenexecuted by computer processor hardware, cause the computer processorhardware (such as one or more co-located or disparately locatedprocessor devices) to: convert an input voltage into an output voltage;select a switching frequency applied to control switching operation ofthe power converter; and transition a setting of the switching frequencyfrom a first clock frequency signal to a second clock frequency signaldepending on detection of phase alignment of the first clock frequencyand the second clock frequency.

The ordering of the steps above has been added for clarity sake. Notethat any of the processing steps as discussed herein can be performed inany suitable order.

Other embodiments of the present disclosure include software programsand/or respective hardware to perform any of the method embodiment stepsand operations summarized above and disclosed in detail below.

It is to be understood that the system, method, apparatus, instructionson computer readable storage media, etc., as discussed herein also canbe embodied strictly as a software program, firmware, as a hybrid ofsoftware, hardware and/or firmware, or as hardware alone such as withina processor (hardware or software), or within an operating system or awithin a software application.

As discussed herein, techniques herein are well suited for use in thefield of supporting switching power supplies. However, it should benoted that embodiments herein are not limited to use in suchapplications and that the techniques discussed herein are well suitedfor other applications as well.

Additionally, note that although each of the different features,techniques, configurations, etc., herein may be discussed in differentplaces of this disclosure, it is intended, where suitable, that each ofthe concepts can optionally be executed independently of each other orin combination with each other. Accordingly, the one or more presentinventions as described herein can be embodied and viewed in manydifferent ways.

Also, note that this preliminary discussion of embodiments herein (BRIEFDESCRIPTION OF EMBODIMENTS) purposefully does not specify everyembodiment and/or incrementally novel aspect of the present disclosureor claimed invention(s). Instead, this brief description only presentsgeneral embodiments and corresponding points of novelty overconventional techniques. For additional details and/or possibleperspectives (permutations) of the invention(s), the reader is directedto the Detailed Description section (which is a summary of embodiments)and corresponding figures of the present disclosure as further discussedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments herein, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, with emphasis instead being placed uponillustrating the embodiments, principles, concepts, etc.

FIG. 1 is an example general diagram of a power supply supportingfrequency switchover according to embodiments herein.

FIG. 2 is an example diagram illustrating a power supply circuitaccording to embodiments herein.

FIG. 3 is an example timing diagram illustrating control signals appliedto the power supply of FIG. 2 according to embodiments herein.

FIG. 4 is an example diagram illustrating a power supply circuitaccording to embodiments herein.

FIG. 5 is an example timing diagram illustrating control signals appliedto the power supply of FIG. 4 according to embodiments herein.

FIG. 6 is an example diagram illustrating eventual phase alignment of afirst clock frequency and a second clock frequency signal over multiplecycles according to embodiments herein.

FIG. 7 is an example diagram illustrating switchover from using a masterclock frequency signal to an asynchronous clock frequency signal back tothe master clock frequency according to embodiments herein.

FIG. 8 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (fixed asynchronous frequency) and a secondclock frequency signal (fixed master frequency) over multiple cycles andcorresponding switchover according to embodiments herein.

FIG. 9 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (asynchronous frequency increasing inmagnitude) and a second clock frequency signal (fixed master frequency)over multiple cycles and corresponding control frequency switchoveraccording to embodiments herein.

FIG. 10 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (asynchronous frequency decreasing inmagnitude) and a second clock frequency signal (fixed master frequency)over multiple cycles and corresponding control frequency switchoveraccording to embodiments herein.

FIG. 11 is an example diagram illustrating a method of controllingfrequency switchover according to embodiments herein.

FIG. 12 is an example diagram illustrating computer processor hardwareand related software instructions to execute methods according toembodiments herein.

FIG. 13 is an example diagram illustrating a method according toembodiments herein.

FIG. 14 is an example diagram illustrating fabrication of a circuitaccording to embodiments herein.

DETAILED DESCRIPTION

An apparatus includes a power converter and a controller. The powerconverter converts a received input voltage into an output voltage thatpowers a dynamic load. The controller controls a setting of a switchingfrequency signal applied to the power converter. During one operationalmode, the controller transitions a setting of the switching frequencysignal of the power converter from a first clock frequency signal to asecond clock frequency signal depending on occurrence of phase alignmentof the second clock frequency signal and the first clock frequencysignal, which may eventually occur over multiple switching controlcycles. Transition of the switching frequency from the first clockfrequency signal to the second clock frequency signal at or around atime of the phase alignment reduces possible perturbations in the outputvoltage as a result of the clock frequency switchover.

Now, more specifically, FIG. 1 is an example general diagram of a powersupply and frequency switchover according to embodiments herein.

As shown in this example embodiment, the power supply 100 includes acontroller 140, power converter 135, and dynamic load 118.

The controller 140 includes control signal generator 141, clockfrequency selector 143, and monitor resource 150. The power converter135 includes components such as switches 125 and/or other circuitry toconvert an input voltage 121 into a respective output voltage 123 thatpowers the dynamic load 118.

During operation, as its name suggests, the monitor resource 150monitors, via feedback 112, one or more attributes of the powerconverter circuit 135 such as magnitude of the input voltage 121,magnitude of the output voltage 123, magnitude of the output current122, etc.

Based on monitored feedback 112, monitor resource 150 produces andoutputs status information 155 indicating settings of the differentmonitored parameters to the clock frequency selector 143.

Via the status information 155, and as its name suggests, the clockfrequency selector 143 associated with the controller 140 produces andoutputs frequency selection control signal 145 to the control signalgenerator 141. In one embodiment, the control signal 145 indicates whichof the clock frequency signals (clock frequency signal 101 or clockfrequency signal 102) is to be used to generate corresponding controlsignals 105 applied to control switching operation of the one or moreswitches 125 in the power converter 135.

As further discussed herein, during one operational mode, the controller140 transitions the setting of the switching frequency of the powerconverter 135 from a first clock frequency signal 101 to a second clockfrequency signal 102 depending on phase alignment of the first clockfrequency signal 101 and the second clock frequency signal 102.

FIG. 2 is an example diagram illustrating a power supply circuitaccording to embodiments herein.

In this example embodiment, the power converter 135 includes inputvoltage source 205 (providing input voltage 121), switches 125 (namely,switch Q1, Q2, Q3, Q4, QR1, QR2, QR3, and QR4), transformer 210,inductor 244, capacitor Cout, and resistor R1.

Transformer 210 includes primary winding 215 and secondary winding 216.

As shown, input voltage source 205 supplies input voltage 121 to node253. Switch Q4 and switch Q3 are connected in series between node 253and node 254. Switch Q1 and switch Q2 are connected in series betweennode 253 and node 254. Node 254 is connected to ground referencevoltage.

Node 251 provides connectivity between a first node of the primarywinding 215 and connection of switches Q1 and Q2. Node 252 providesconnectivity between a second node the primary winding 215 and switchesQ3 and Q4.

As further shown, switch QR1 and switch QR4 are connected in seriesbetween node 263 and node 264. Switch QR2 and switch QR3 are connectedin series between node 263 and node 264.

Node 261 provides connectivity between a first node of the secondarywinding 216 and connect between switches QR1 and QR4. Node 262 providesconnectivity between a second node of the secondary winding 216 andconnection between switches QR2 and QR3.

As previously discussed, controller 140 produces control signals 105including signal S1, signal S2, signal S3, signal S4, signal SR1, signalSR2, signal SR3, and signal SR4 driving respective switches 125. Forexample, in this example embodiment, control signal S1 controls gate (G)of switch Q1; control signal S2 controls gate (G) of switch Q2; controlsignal S3 controls gate (G) of switch Q3; control signal S4 controlsgate (G) of switch Q4; control signal SR1 controls gate (G) of switchQR1; control signal SR2 controls gate (G) of switch QR2; control signalSR3 controls gate (G) of switch QR3; control signal SR4 controls gate(G) of switch QR4.

Inductor 244 is connected between node 263 and node 266. Outputcapacitor Cout is connected between node 266 and ground referencevoltage 267. Node 266 produces output voltage 123 that powers dynamicload 118.

FIG. 3 is an example timing diagram illustrating control signals appliedto the power supply of FIG. 2 according to embodiments herein.

Timing diagram 300 indicates states of respective control signalsdriving switches 125.

For example, controller 140 sets the signal S1 to a logic high betweentime T2 and T3, turning ON respective switch Q1 resulting in a lowresistance drain to source switch path; controller 140 sets the signalS2 to a logic high between time T6 and T7, turning ON respective switchQ2 resulting in a low resistance drain to source switch path; controller140 sets the signal S3 to a logic high between time T2 and T3, turningON respective switch Q3 resulting in a low resistance drain to sourceswitch path; controller 140 sets the signal S4 to a logic high betweentime T6 and T7, turning ON respective switch Q4 resulting a lowresistance drain to source switch path. Such control signals areotherwise logic low (respective switches are OFF).

Controller 140 sets the signal SR1 to a logic low between time T5 andT8, turning OFF respective switch QR1 resulting in a high resistancedrain to source switch path; controller 140 sets the signal SR2 to alogic low between time T1 and T4, turning OFF respective switch QR2resulting in a high resistance drain to source switch path; controller140 sets the signal SR3 to a logic low between time T5 and T8, turningOFF respective switch QR3 resulting in a high resistance drain to sourceswitch path; controller 140 sets the signal SR4 to a logic low betweentime T1 and T4, turning OFF respective switch QR4 resulting in a highresistance drain to source switch path. Such control signals areotherwise logic high (respective switches are ON).

Time duration between time 0 and TSW represents one period of arespective switching control cycle of controlling the power converter135. The corresponding switching frequency=1/TSW.

Switching of respective switches Q1, Q2, Q3, and Q4 as previouslydiscussed produces voltage V1 at the input of the primary winding 215.Switching of switches QR1, QR2, QR3, and QR4 produces the output voltage123 (Vout such as a DC voltage).

FIG. 4 is an example diagram illustrating a power supply circuitaccording to embodiments herein.

In this embodiment, the instantiation of power supply 100-2 includemultiple phases such as phase 401 and phase 402. Controller 140 producessignals S11, S12, SR11, and SR12. Controller 140 also produces signalsS21, S22, SR21, and SR22.

As shown, transformer 410-1 of phase 410 includes primary winding 416-1and a secondary winding. The secondary winding is centered tapped toinclude secondary winding 416-1 and secondary winding 416-2.

Phase 401 further includes: i) series connected capacitors C12 and C13between the node 491 and node 492, and ii) series connected switches Q11and Q12 between the node 491 and node 492. A first node of primarywinding 415-1 is connected to the node connecting capacitors C12 andC13; a second node of primary winding 415-1 is connected to the nodeconnecting switches Q11 and Q12.

A first node of primary winding 416-1 is connected to the drain node ofswitch QR12; the source node of switch QR12 is connected to resistorR12. A first node of primary winding 417-1 is connected to the drainnode of switch QR11; the source node of switch QR11 is connected to afirst node of resistor R12. A second node of resistor R12 is connectedto ground node 499. Inductor 444-1 is connected between the node 498 andnode coupling secondary winding 416-1 and secondary winding 417-1. Eachof the components such as capacitor C11, resistor R11, and load 118 isconnected between node 498 and node 499.

Phase 402 further includes: i) series connected capacitors C22 and C23between the node 491 and node 492, and ii) series connected switches Q21and Q22 between the node 491 and node 492. A first node of primarywinding 415-2 is connected to the node connecting capacitors C22 andC23; a second node of primary winding 415-2 is connected to the nodeconnecting switches Q21 and Q22.

A first node of primary winding 416-2 is connected to the drain node ofswitch QR22; the source node of switch QR22 is connected to a first nodeof resistor R22. A first node of primary winding 417-2 is connected tothe drain node of switch QR21; the source node of switch QR21 isconnected to the first node of resistor R22. A second node of resistorR22 is connected to ground node 499. Inductor 444-2 is connected betweenthe node 498 and node coupling secondary winding 416-2 and secondarywinding 417-2. Each of the components such as capacitor C21, resistorR21, and load 118 is connected between node 498 and node 499.

The combination of phases 401 and 402 produce a respective outputvoltage 123 powering dynamic load 118.

FIG. 5 is an example timing diagram illustrating control signals appliedto the power supply of FIG. 4 according to embodiments herein.

Timing diagram 500 indicates states of respective control signalsdriving switches 125.

For example, controller 140 sets the signal S11 to a logic high betweentime T12 and T13, turning ON respective switch Q11 resulting in a lowresistance drain to source switch path; controller 140 sets the signalS12 to a logic high between time T16 and T17, turning ON respectiveswitch Q12 resulting in a low resistance drain to source switch path;controller 140 sets the signal SR11 to a logic low between time T15 andT18, turning OFF respective switch QR11 resulting in a high resistancedrain to source switch path; controller 140 sets the signal SR12 to alogic low between time T11 and T14, turning OFF respective switch QR12resulting in a high resistance drain to source switch path.

Controller 140 sets the signal S21 to a logic high between time T14 andT15, turning ON respective switch QR21 resulting in a low resistancedrain to source switch path; controller 140 sets the signal S22 to alogic low between time T11 and T18, turning OFF respective switch QR22resulting in a high resistance drain to source switch path; controller140 sets the signal SR21 to a logic high between time T12 and T17,turning ON respective switch QR21 resulting in a low resistance drain tosource switch path; controller 140 sets the signal SR22 to a logic lowbetween time T13 and T16, turning OFF respective switch QR22 resultingin a high resistance drain to source switch path.

Time duration between time 0 and TSW represents one period of arespective switching control cycle of controlling the power converter135. The corresponding switching frequency=1/TSW.

Switching of respective switches Q11, Q12, Q21, Q22, QR11, QR12, QR21,and QR22, as previously discussed produces the output voltage 123 (Voutsuch as a DC voltage or substantially DC voltage).

FIG. 6 is an example diagram illustrating eventual phase alignment of afirst clock frequency and a second clock frequency signal over multiplecycles according to embodiments herein.

As previously discussed, during one operational mode, the controller 140transitions the setting of the switching frequency of the powerconverter 135 from a first clock frequency signal 101-1 to a secondclock frequency signal 102-1 depending on phase alignment of the firstclock frequency signal 101-1 and the second clock frequency signal102-1. Timing diagram 600 illustrates how the phase of clock frequency101-1 and clock frequency 102-1 are initially out of phase for multiplecycles until alignment at time, Talign.

FIG. 7 is an example diagram illustrating switchover from using a masterclock frequency signal to an asynchronous clock frequency signal inresponse to detecting a transient condition according to embodimentsherein.

While in mode #1, the controller 140 produces respective control signals105 for cycle #1 and cycle #2 based on a master clock frequency signal102. In one embodiment, the value setting (such as magnitude) of themaster clock frequency signal 102 is chosen so that generation of theoutput voltage 123 does not interfere with electronics powered by theoutput voltage 123 (and corresponding output current 122).

Prior to time Tswitchover1 (such as cycle #1, cycle #2, the controller140 use the clock frequency signal 102 to generate corresponding controlsignals driving the power converter circuit 135. In one embodiment, whenthe controller 140 commits to switching from a transient response (TR)mode/discontinuous conduction mode (DCM) frequency (first frequency 101)to standard frequency (second frequency 102), such as from mode #2 tomode #1, the controller 140 implements an intermediate frequency, whichthe controller 140 chooses so that phase alignment occurs in a fewswitching cycles. For example, as further discussed below in FIG. 8, inone embodiment, the controller 140 sets the first clock frequency signal101 and the second clock frequency signal 102 to different desired fixedfrequency settings just prior to the transition of setting the switchingfrequency to the second clock frequency signal. In yet further exampleembodiments, the controller 140 can be configured to adjust a value ofthe first clock frequency signal 101 (such as an intermediate frequency)to be within a threshold value (such as 20% percent of point of thefirst clock frequency or other suitable value) of the second clockfrequency signal 102 in response to detecting a trigger event(notification from clock frequency selector 143) to set the switchingfrequency of the power converter 135 back to the second clock frequencysignal 102.

At or around time Tswitchover1, assume that the monitor resource 150detects a change in magnitude of the output voltage 123 and/or theoutput current 122 due to a transient consumption condition associatedwith the dynamic load 118. To maintain the output voltage 123 within adesired voltage range, and provide continued voltage regulation, thecontroller 140 switches over to operating the power converter 135 via ahigher switching frequency signal 101 during mode #2 (such as cycle #3,cycle #4, cycle #5, etc.).

In mode #2, the controller 140 controls one or more parameters such as afrequency setting of the controls signals 125, pulse width of controlsignals 125, etc., to maintain the output voltage 123 in a desiredrange. As previously discussed, it may be less desirable to operate offa different frequency than the master clock frequency 102. However,switching over to the clock frequency signal 101 ensures that themagnitude of the output voltage 123 is maintained within an appropriatevoltage range.

Thus, in response to detecting a condition such as a change in an amountof current consumed by a load 118, variation in a magnitude of theoutput voltage 123, or any other power supply condition, the controller140 temporarily sets the switching frequency signal applied to the powerconverter to the first clock frequency signal 101 (such as a higherfrequency operation that is needed) to maintain regulation of the outputvoltage 123 within a desired range due to a transient condition. Thus,one embodiment herein includes the controller 140 switching (at timeTswitchover 1) from setting the switching frequency from the secondclock frequency signal 102 to the first clock frequency signal 101 inresponse to detecting a substantial change in current consumption by thedynamic load.

Eventually, after a transient load condition is over (normal currentconsumption), such as determined via monitoring of the output voltage123 and/or output current 122 using monitor resource 150, the controller150 switches back to operating in mode #1 at time Tswitchover2. However,as shown, the transition from operating off the first clock frequencysignal 101 to operating off the second clock frequency signal 102 occursdepending on alignment of the first clock frequency signal 101 and thesecond clock frequency signal 102 as further discussed below.

In other words, as further discussed below, the decision to switchoverto the second clock frequency 102 occurs at or around time 82. However,the transition from the clock frequency signal 101 to the clockfrequency signal 102 does not occur until time T90 when the phases aresubstantially aligned.

Thus, FIG. 7 illustrates how the switching frequency of operating thepower converter circuit 135 becomes temporarily asynchronous withrespect to the master clock frequency signal 102 during mode #2.However, re-synchronization of operating the power converter circuit 135to the master clock frequency signal 102 eventually occurs upondetection of phase alignment as further discussed below.

FIG. 8 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (fixed asynchronous frequency) and a secondclock frequency signal (fixed master frequency) over multiple cycles andcorresponding switchover according to embodiments herein.

As previously discussed, in one embodiment, subsequent to addressing(providing sufficient current to accommodate) the transient loadcondition, assume that the first clock frequency signal 101 (measuredvia the control cycle between T80 and T82, control cycle between T82 andT84, control cycle between T84 and T86, control cycle between T86 andT88, etc.) and the second clock frequency signal 102 (measured via thecontrol cycle between T81 and T83, control cycle between T83 and T85,control cycle between T85 and T87, control cycle between T87 and T89,etc.) are not aligned. For example, as shown, for several clock cyclesbefore time Tswitchover, the clock frequency signal 101 and clockfrequency signal 102 are out of phase with respect to each other.

However, because the first clock frequency signal 101 and the secondclock frequency signal 102 are different in magnitude (such as becausethe clock frequency signal 101 is set to a higher frequency than themaster clock frequency signal 102, eventually the first clock frequencysignal 101 and the second clock frequency signal 102 align over multipleswitching control cycles at time Tswitchover2 (around time T89 and T90).

Recall again that the second clock frequency is a master clock frequencysignal 102 synchronized to an external clock source; the first clockfrequency signal 101 is asynchronous with respect to the master clockfrequency to accommodate transient control. Operation of the powerconverter 135 at the higher switching frequency (variable clockfrequency signal 101) increases a responsiveness of the power converter135 to maintain the output voltage 123 in regulation during transientcurrent consumption conditions. Additionally, in certain instances, thecontroller 140 varies a value of the first clock frequency signal 101 aswell as corresponding pulse width modulation signals applied to thepower converter 135 (over any frequency control signals) to maintain amagnitude of the output voltage 123 within a desired operational range.

Assume that the frequency selection control signal 145 from the clockfrequency selector 143 indicates to switchover at around time T80 orT81. As previously discussed, the controller 140 does not initiallyswitch to (re-synchronize) operating the power converter 135 andproducing respective control signals 105 based on the master clockfrequency signal 102 until time Tswitchover2 when the phase of the clockfrequency signal 102 aligns substantially, as shown, with the phase ofthe clock frequency signal 101.

In one embodiment, the controller 140 sets the first clock frequencysignal 101 and the second clock frequency signal 102 to differentdesired fixed frequency settings just prior to the transition of settingthe switching frequency to the second clock frequency signal. Forexample, the controller 140 can be configured to adjust a value of thefirst clock frequency signal 101 (such as an intermediate frequency) tobe within a threshold value (such as 20% percent of point of the firstclock frequency or other suitable value) of the second clock frequencysignal 102 in response to detecting a trigger event (notification fromclock frequency selector 143) to set the switching frequency of thepower converter 135 back to the second clock frequency signal 102.

In one embodiment, the controller 140 sets a value (i.e. magnitude) ofthe first clock frequency signal 101 to a value that is different, butsubstantially equal to but greater in value than a value of the masterclock frequency signal 102. That is, the clock frequency signal 101 andthe (fixed) master clock frequency signal 102 are not equal in value(magnitude) during mode #2. The difference in the values of the firstclock frequency signal 101 and the master clock frequency signal 102(one frequency being greater than the other) eventually causes thephases of these different clock frequency signals to align, enablingtransition as described herein.

More specifically, time duration D11 illustrates an amount by which theclock frequency signal 102 is out of phase with respect to clockfrequency signal 101 around time T81 and time T82. Time duration D12illustrates an amount by which the clock frequency signal 102 is out ofphase with respect to clock frequency signal 101 around time T83 andtime T84. Time duration D13 illustrates an amount by which the clockfrequency signal 102 is out of phase with respect to clock frequencysignal 101 around time T85 and time T86. Time duration D14 illustratesan amount by which the clock frequency signal 102 is out of phase withrespect to clock frequency signal 101 around time T87 and time T88. Timeduration D15 illustrates an amount by which the clock frequency signal102 is out of phase with respect to clock frequency signal 101 aroundtime T89 and time T90.

Thus, the phase difference between the second clock frequency signal 102and the first clock frequency signal 101 decreases over multipleswitching control cycles until eventual alignment.

The transition of the switching frequency from using the first frequencysignal 101 to the second frequency signal 102 at or around the time ofalignment (Tswitchover2) substantially reduces or prevents perturbationsin the output voltage 123 (and/or disturbance to the circuit) as aresult of the clock frequency transition. In other words, initiatingswitchover from the first clock frequency signal 101 to the second clockfrequency signal 102 at time Tswitchover provides a smoother controltransition.

As previously discussed, in one embodiment, the second clock frequencysignal 102 is a predetermined fixed (master) frequency that does notchange because it synchronized with a corresponding circuit and/or oneor more remote clocks. Thus, even though the controller 140 may initiatea switchover at time T82 in FIG. 7, the control continues to tracktiming of the master clock frequency signal 102 for subsequentswitchover at time Tswitchover2. In a manner as previously discussed,the controller 140 transitions from setting the switching frequency fromthe first clock frequency to the second clock frequency in response tothe controller (or other suitable resource) detecting that a phase ofthe second clock frequency signal 102 substantially aligns with a phaseof the first clock frequency 101 or in response to detecting that aphase of the first clock frequency signal 101 substantially aligns witha phase of the second clock frequency signal 102.

FIG. 9 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (asynchronous frequency increasing invalue) and a second clock frequency signal (fixed master frequency) overmultiple cycles and corresponding control frequency switchover accordingto embodiments herein.

In one embodiment, as shown in FIG. 9, the controller 140 adjusts afrequency value of the first clock frequency signal 101 over multiplecontrol cycles such as between time T91 and time T98.

More specifically, in a manner as previously discussed, time durationD21 illustrates an amount by which the clock frequency signal 102 is outof phase with respect to clock frequency signal 101 around time T92 andtime T93. Time duration D22 illustrates an amount by which the clockfrequency signal 102 is out of phase with respect to clock frequencysignal 101 around time T94 and time T95. Time duration D23 illustratesan amount by which the clock frequency signal 102 is out of phase withrespect to clock frequency signal 101 around time T96 and time T97.

In one embodiment, because the first clock frequency signal 101 andclock frequency signal 102 are substantially aligned at or around timeT96 and T97, the controller 140 switches over to using the master clockfrequency signal 102 to generate the controls signals 105 that controlthe power converter 135.

Thus, via adjustment of the clock frequency signal 101, the phasedifference between the second clock frequency signal 102 and the firstclock frequency signal 101 more quickly decreases over multipleswitching control cycles. The transition of the switching frequency fromthe first frequency signal 101 to the second frequency signal 102 at oraround the time of alignment substantially reduces or preventsperturbations in the output voltage 123 (and/or disturbance to thecircuit) as a result of the clock frequency transition. In other words,initiating switchover from the first clock frequency signal 101 to thesecond clock frequency signal 102 at time Tswitchover provides asmoother control transition.

Thus, embodiments herein include, in addition to the controller 140adjusting a clock frequency of the first clock frequency signal 101, thecontroller 140 transitions the setting of the switching frequency fromthe first clock frequency signal 101 to the master clock frequencysignal 102 depending on detection of a phase difference between thefirst clock frequency signal 101 with respect to the master clockfrequency signal 102; the phase difference decreases in magnitude overmultiple switching control cycles until switchover as previouslydiscussed.

FIG. 10 is an example diagram illustrating eventual phase alignment of afirst clock frequency signal (asynchronous frequency decreasing invalue) and a second clock frequency signal (fixed master frequency) overmultiple cycles and corresponding control frequency switchover accordingto embodiments herein.

In one embodiment, as shown in FIG. 10, the controller 140 adjusts afrequency value of the first clock frequency signal 101 over multiplecontrol cycles such as between time T101 and time T108.

Time duration D31 illustrates an amount by which the clock frequencysignal 102 is out of phase with respect to clock frequency signal 101around time T103 and time T104. Time duration D32 illustrates an amountby which the clock frequency signal 102 is out of phase with respect toclock frequency signal 101 around time T105 and time T106. Time durationD33 illustrates an amount by which the clock frequency signal 102 is outof phase with respect to clock frequency signal 101 around time T107 andtime T108.

In one embodiment, because the first clock frequency signal 101 andclock frequency signal 102 are substantially aligned at or around timeT107 and T108, the controller 140 switches over to using the masterclock frequency signal 102 to generate the controls signals 105 thatcontrol the power converter 135.

Thus, via reducing the frequency of the clock frequency signal 101 overtime, the phase difference between the second clock frequency signal 102and the first clock frequency signal 101 more quickly decreases overmultiple switching control cycles, resulting quicker alignment.

FIG. 11 is an example diagram illustrating a method of controllingfrequency switchover according to embodiments herein.

Flowchart 1100 illustrates initial operation 1110 of the power converter135 in the mode #1 based on the master clock frequency signal 102.

In processing operation 1120, the controller 140 determines whether atransient current consumption condition occurs via a change in thedynamic load 118. If not processing continues in operation 1110. If so,operation continues at processing operation 1130.

In processing operation 1130, the controller 140 operates in mode #2 aspreviously discussed.

In processing operation 1140, the controller 140 determines if it candiscontinue operating the power converter 135 in mode #2 using the firstclock frequency signal 101. If not, processing continues at processingoperation 1130. If so, the controller executes processing operation 1150in which the controller 140 monitors for phase alignment in a manner aspreviously discussed. If the transient current consumption still existsin processing operation 1190, the controller 140 stays in mode #2.

In processing operation 1160, the controller 140 determines if thephases align in a manner as previously discussed. If so, and thecontroller 140 detects phase alignment in processing operation 1170 andprocessing operation 1180 (and there is no longer a transient currentconsumption condition), the controller 140 continues execution atprocessing operation 1110.

FIG. 12 is an example block diagram of a computer device forimplementing any of the operations as discussed herein according toembodiments herein.

As shown, computer system 1200 (such as implemented by any of one ormore resources such as controller 140, control signal generator 141,clock frequency selector 143, monitor resource 150, etc.) of the presentexample includes an interconnect 1211 that couples computer readablestorage media 1212 such as a non-transitory type of media (or hardwarestorage media) in which digital information can be stored and retrieved,a processor 1213 (e.g., computer processor hardware such as one or moreprocessor devices), I/O interface 1214, and a communications interface1217.

I/O interface 1214 provides connectivity to any suitable circuitry suchas power converter circuit 135.

Computer readable storage medium 1212 can be any hardware storageresource or device such as memory, optical storage, hard drive, floppydisk, etc. In one embodiment, the computer readable storage medium 1212stores instructions and/or data used by the control application 140-1 toperform any of the operations as described herein.

Further in this example embodiment, communications interface 1217enables the computer system 1200 and processor 1213 to communicate overa resource such as network 190 to retrieve information from remotesources and communicate with other computers.

As shown, computer readable storage media 1212 is encoded with controlapplication 140-1 (e.g., software, firmware, etc.) executed by processor1213. Control application 140-1 can be configured to includeinstructions to implement any of the operations as discussed herein.

During operation of one embodiment, processor 1213 accesses computerreadable storage media 1212 via the use of interconnect 1211 in order tolaunch, run, execute, interpret or otherwise perform the instructions incontrol application 140-1 stored on computer readable storage medium1212.

Execution of the control application 140-1 produces processingfunctionality such as control process 140-2 in processor 1213. In otherwords, the control process 140-2 associated with processor 1213represents one or more aspects of executing control application 140-1within or upon the processor 1213 in the computer system 1200.

In accordance with different embodiments, note that computer system 1200can be a micro-controller device, logic, hardware processor, hybridanalog/digital circuitry, etc., configured to control a power supply andperform any of the operations as described herein.

Functionality supported by the different resources will now be discussedvia flowchart in FIG. 13. Note that the steps in the flowcharts belowcan be executed in any suitable order.

FIG. 13 is an example diagram illustrating a method of controlling apower converter according to embodiments herein.

In processing operation 1310, the power converter 135 converts the inputvoltage 121 into an output voltage 123.

In processing operation 1320, the controller 140 selects a switchingfrequency signal applied to control switching operation of the powerconverter 135.

In processing operation 1330, the controller 140 transitions a settingof the switching frequency of the power converter 135 from a first clockfrequency signal 101 to a second clock frequency signal 102 (such asre-synchronization) depending on phase alignment.

In one embodiment, FIG. 13 illustrates a transition from a non-standardfrequency (such as operating off clock frequency signal 1010 to astandard frequency (such as clock frequency signal 102). As previouslydiscussed, the controller 140 and related resources initiate thetransition when switching from a Transient Response (TR) mode orDiscontinuous conduction mode (DCM) to a normal mode.

Further, as previously discussed with respect to FIG. 7, switching fromoperating in mode #1 to mode #2 at time Tswitchover 1 is more abrupt toensure that the output voltage stays within regulation. In other words,switchover is instantaneous. This is because the controller 140 hascontrol of the phase of the non-standard frequency clock (clockfrequency signal 101) and selects an exact phase needed to accommodatethe detected transient condition.

Thus, there is this asymmetry in switching from different modes. Forexample, transitioning from standard mode #1 to non-standard mode #2 isfast or immediate; transitioning from non-standard mode #2 to standardmode 1 depends on the phase alignment of the clocks (which may requiremultiple clock cycles) as previously discussed. In one embodiment, aspreviously discussed, this is because the clock frequency signal 102 isset to a fixed frequency and their no control over its phases.

FIG. 14 is an example diagram illustrating fabrication of a powerconverter circuit on a circuit board according to embodiments herein.

In this example embodiment, fabricator 1440 receives a substrate 1410(such as a circuit board).

The fabricator 1440 further affixes the controller 140 and powerconverter 135 (and corresponding components) to the substrate 1410. Viacircuit paths 1421 (such as one or more traces, etc.), the fabricator1440 couples the controller 140 to the power converter 135.

Via one or more circuit paths 1422 (such as one or more traces, etc.),the fabricator 1440 couples the power converter 135 to the load 128. Inone embodiment, the circuit path 1422 conveys the output voltage 123generated from the power converter 100 to the load 118.

Accordingly, embodiments herein include a system comprising: a substrate1410 (such as a circuit board, standalone board, mother board,standalone board destined to be coupled to a mother board, etc.); apower converter 135 including corresponding components as describedherein; and a load 118. As previously discussed, the load 118 is poweredbased on conveyance of output voltage 123 and corresponding current 132conveyed over one or more circuit paths 1422 from the power converter100 to the load 118.

Note that the load 118 can be any suitable circuit or hardware such asone or more CPUs (Central Processing Units), GPUs (Graphics ProcessingUnit) and ASICs (Application Specific Integrated Circuits such thoseincluding one or more Artificial Intelligence Accelerators), which canbe located on the substrate 1410 or disposed at a remote location.

Note again that techniques herein are well suited for use in circuitapplications such as those that implement power conversion. However, itshould be noted that embodiments herein are not limited to use in suchapplications and that the techniques discussed herein are well suitedfor other applications as well.

Based on the description set forth herein, numerous specific detailshave been set forth to provide a thorough understanding of claimedsubject matter. However, it will be understood by those skilled in theart that claimed subject matter may be practiced without these specificdetails. In other instances, methods, apparatuses, systems, etc., thatwould be known by one of ordinary skill have not been described indetail so as not to obscure claimed subject matter. Some portions of thedetailed description have been presented in terms of algorithms orsymbolic representations of operations on data bits or binary digitalsignals stored within a computing system memory, such as a computermemory. These algorithmic descriptions or representations are examplesof techniques used by those of ordinary skill in the data processingarts to convey the substance of their work to others skilled in the art.An algorithm as described herein, and generally, is considered to be aself-consistent sequence of operations or similar processing leading toa desired result. In this context, operations or processing involvephysical manipulation of physical quantities. Typically, although notnecessarily, such quantities may take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared orotherwise manipulated. It has been convenient at times, principally forreasons of common usage, to refer to such signals as bits, data, values,elements, symbols, characters, terms, numbers, numerals or the like. Itshould be understood, however, that all of these and similar terms areto be associated with appropriate physical quantities and are merelyconvenient labels. Unless specifically stated otherwise, as apparentfrom the following discussion, it is appreciated that throughout thisspecification discussions utilizing terms such as “processing,”“computing,” “calculating,” “determining” or the like refer to actionsor processes of a computing platform, such as a computer or a similarelectronic computing device, that manipulates or transforms datarepresented as physical electronic or magnetic quantities withinmemories, registers, or other information storage devices, transmissiondevices, or display devices of the computing platform.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of the presentapplication as defined by the appended claims. Such variations areintended to be covered by the scope of this present application. Assuch, the foregoing description of embodiments of the presentapplication is not intended to be limiting. Rather, any limitations tothe invention are presented in the following claims.

1. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein a phase difference between the first clock frequency signal and the second clock frequency signal decreases for multiple cycles just prior to the transition; and wherein the phase difference between the first clock frequency signal and the second clock frequency signal increases for multiple cycles just after the transition.
 2. The apparatus as in claim 1, wherein the controller is operative to monitor the phase alignment of the first clock frequency signal and the second clock frequency signal, the phase alignment changing over each of multiple control cycles of controlling the switching frequency.
 3. The apparatus as in claim 1, wherein the first clock frequency signal is different, but substantially equal to the second clock frequency signal.
 4. The apparatus as in claim 1, wherein the first clock frequency signal and the second clock frequency signal are each set to a different fixed frequency setting for the multiple switching control cycles just prior to the transition of setting the switching frequency to the second clock frequency signal.
 5. The apparatus as in claim 1, wherein the transition from setting the switching frequency from the first clock frequency signal to the second clock frequency signal occurs in response to the controller detecting that a phase of the second clock frequency signal aligns with a phase of the first clock frequency signal.
 6. The apparatus as in claim 1, wherein the controller is operative to transition the setting of the switching frequency from the first clock frequency signal to the second clock frequency signal depending on a phase difference between the first clock frequency signal with respect to the second clock frequency signal, the phase difference decreasing in magnitude over the multiple cycles.
 7. The apparatus as in claim 1, wherein the second clock frequency signal is a master clock frequency signal, the first clock frequency signal being asynchronous with respect to the master clock frequency signal.
 8. The apparatus as in claim 1, wherein the second clock frequency signal is a predetermined fixed frequency signal in which to operate the power converter during non-transient load conditions.
 9. The apparatus as in claim 1, wherein the controller varies the first clock frequency signal depending on a magnitude of current consumption by a dynamic load powered by the output voltage of the power converter.
 10. The apparatus as in claim 1, wherein the controller is operative to switchover from setting the switching frequency from the second clock frequency signal to the first clock frequency signal in response to detecting a change in current consumption by the dynamic load, the first clock frequency signal being greater in value than the second clock frequency signal.
 11. The apparatus as in claim 1, wherein the controller is operative to adjust a setting of the first clock frequency signal, adjustment of the first clock frequency signal resulting in the phase alignment of the first clock frequency signal and the second clock frequency signal in fewer switching control cycles.
 12. The apparatus as in claim 1, wherein the controller is operative to adjust a setting of the first clock frequency signal, the first clock frequency signal being adjusted within a threshold value of the second clock frequency signal in response to detecting a trigger event to set the switching frequency of the power converter back to the second clock frequency signal.
 13. A method comprising: via a power converter, converting an input voltage into an output voltage; selecting a switching frequency applied to control switching operation of the power converter; transitioning a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein a phase difference between the first clock frequency signal and the second clock frequency signal decreases for multiple cycles just prior to the transition of the setting; and wherein the phase difference between the first clock frequency signal and the second clock frequency signal increases for multiple cycles just after the transition of the setting.
 14. The method as in claim 13 further comprising: monitoring the phase alignment of the first clock frequency signal and the second clock frequency signal, a magnitude of the phase alignment changing over each of the multiple cycles.
 15. The method as in claim 13, wherein the first clock frequency signal is different but substantially equal to the second clock frequency signal.
 16. The method as in claim 13, wherein the first clock frequency signal and the second clock frequency signal are set to different fixed frequency settings just prior to the transition of setting the switching frequency to the second clock frequency signal.
 17. The method as in claim 13, wherein transitioning from the setting of the switching frequency from the first clock frequency signal to the second clock frequency signal occurs in response to detecting that a phase of the second clock frequency signal substantially aligns with a phase of the first clock frequency signal.
 18. The method as in claim 13, wherein transitioning the setting of the switching frequency from the first clock frequency signal to the second clock frequency signal depends on a detected phase difference between the second clock frequency signal with respect to the first clock frequency signal.
 19. The method as in claim 13, wherein the second clock frequency signal is a master clock frequency signal, the first clock frequency signal being an asynchronous clock frequency signal with respect to the master clock frequency signal.
 20. The method as in claim 13, wherein the second clock frequency signal is a predetermined fixed frequency signal in which to operate the power converter during non-transient load conditions.
 21. The method as in claim 13 further comprising: varying a value of the first clock frequency signal depending on a magnitude of current consumption by a dynamic load powered by the output voltage of the power converter.
 22. The method as in claim 13 further comprising: switching over from setting the switching frequency from the second clock frequency signal to the first clock frequency signal controlling the power converter in response to detecting a change in current consumption provided by the output voltage, the first clock frequency being greater in value than the second clock frequency.
 23. The method as in claim 13 further comprising: adjusting a value of the first clock frequency signal, adjustment of the first clock frequency signal resulting in the phase alignment of the first clock frequency signal and the second clock frequency signal in fewer switching control cycles.
 24. The method as in claim 13 further comprising: adjusting a value of the first clock frequency signal, the first clock frequency signal being adjusted within a threshold value of the second clock frequency signal in response to detecting a trigger event to set the switching frequency of the power converter back to the second clock frequency signal.
 25. Computer-readable storage media having instructions stored thereon, the instructions, when executed by computer processor hardware, cause the computer processor hardware to: convert an input voltage into an output voltage; select a switching frequency applied to control switching operation of the power converter; transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein a phase difference between the first clock frequency signal and the second clock frequency signal decreases for multiple cycles just prior to the transition; and wherein the phase difference between the first clock frequency signal and the second clock frequency signal increases for multiple cycles just after the transition.
 26. A system comprising: a circuit substrate; the apparatus of claim 1, the apparatus fabricated on the circuit substrate; and a load, the load powered by the output voltage.
 27. A method comprising: receiving a circuit substrate; and fabricating the apparatus of claim 1 on the circuit substrate.
 28. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein the controller is operative to monitor the phase alignment of the first clock frequency signal and the second clock frequency signal, the phase alignment changing over each of multiple control cycles of controlling the switching frequency; and wherein the controller is further operable to, during the transition: i) set the switching frequency to the first clock frequency signal for first cycles of the multiple cycles, ii) detect the phase alignment while the switching frequency is set to the first clock frequency signal, and iii) switchover to setting the switching frequency to the second clock frequency signal in response to the phase alignment of the first clock frequency signal and the second clock frequency signal.
 29. (canceled)
 30. An apparatus comprising: a power converter to convert an input voltage into an output voltage; and a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein the phase alignment of the first clock frequency signal and the second clock frequency signal includes alignment of an edge of the first clock frequency signal to an edge of the second clock signal.
 31. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein the first clock frequency signal is a master clock frequency signal, the second clock frequency signal being asynchronous with respect to the master clock frequency signal; and wherein the controller is further operable to: transition the setting of the switching frequency from the second first clock frequency signal to the first clock frequency signal depending on phase alignment of the second clock frequency signal and the first clock frequency signal.
 32. The apparatus as in claim 31, wherein the controller is operative to switchover the setting of the switching frequency from the first clock frequency signal to the second clock frequency signal in response to detecting a change in current consumed by a load powered by the output voltage, the output voltage supplying current to the load.
 33. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; and wherein the first clock frequency signal and the second clock frequency signal are temporarily aligned at a time of the transition.
 34. The apparatus as in claim 1, wherein the controller is further operable to transition from the first clock frequency signal to the second clock frequency signal at a time in which an edge of the second clock frequency signal does not align with an edge of the first clock frequency signal.
 35. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; and wherein the first clock frequency signal is synchronized with a clock of a remote circuit.
 36. An apparatus comprising: a power converter to convert an input voltage into an output voltage; a controller operative to: i) control a setting of a switching frequency applied to control switching operation of the power converter, and ii) transition a setting of the switching frequency from a first clock frequency signal to a second clock frequency signal in response to detected phase alignment of the first clock frequency signal and the second clock frequency signal; wherein the controller is further operable to: at a first time instant, determine a condition in which to switchover the switching frequency from the first clock frequency signal to the second clock frequency signal, the condition occurring multiple clock cycles prior to the transition; and wherein the transition occurs a at a second time instant, the second time instant being delayed with respect to the first time instant.
 37. The apparatus as in claim 36, wherein the first clock frequency signal and the second clock frequency signal are not aligned at the first time instant. 